This application claims the benefit of Korean Application No. 2000-57689, filed Sep. 30, 2000, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method of correcting a print error of an inkjet printer, and more particularly, to a method of correcting a print error caused by misalignment between a plurality of chip,s mounted on an array head of the inkjet printer.
2. Description of the Related Art
Generally, compared to a shuttle type inkjet printer that conveys one chip for printing, an array head type inkjet printer uses a plurality of chips to print at a higher speed. Although the array head type inkjet printer prints at the higher speed, it also has a higher possibility of having deteriorated print quality even with a minute deviation of the chips from a designated position.
The print quality deterioration will now be described in greater detail with reference to FIGS. 1 through 3. Referring to FIG. 1, an array head 1 of an inkjet printer includes a print bar 10, and a plurality of unit chips 20. Each unit chip 20 has a plurality of nozzles 31 through which ink droplets are ejected. The nozzles 31 form a nozzle group 30. For example, as shown in FIG. 1, there are six nozzle groups 30, each consisting of six nozzles 31 on one unit chip 20.
As shown in FIG. 2A, a line is printed as the ink droplets are ejected onto a printing medium from the first nozzle 31 of the nozzle group 30 of the unit chip 20, and then from the second, and third through sixth nozzles 31, sequentially. A period (T) of a voltage application to heaters (not shown) of the respective nozzles 31 is obtained by the following formula:
xe2x80x83xcfx84=U/c[d]xe2x80x83xe2x80x83Formula 1
where U is a printing medium feeding speed, and c is a vertical distance between two nozzles 31.
As shown in FIG. 3, the unit chips 20 are mounted on the print bar 10, the unit chips 20 are frequently deviated from the ideal position due to a machine error, causing misalignment between the unit chips 20. There are three types of misalignment, i.e., a rotation by tilting (e), a horizontal translation (xcex4n) and a vertical translation (xcex4v) of the unit chips 20. Only a minute degree of misalignment causes a white band and a dark line to form, thus the print quality deteriorates.
Accordingly, it is an object of the present invention to provide a method of a print error caused due to misalignment between unit chips, which occurs while mounting a plurality of the unit chips on a print bar of an array head type inkjet printer.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The above and other objects are accomplished by a method of correcting a print error caused due to a misalignment between unit chips mounted on an array head of an inkjet printer in accordance with the present invention, including calculating an acceptable limit of a rotation angle of the unit chips with respect to reference positions, within a range that does not cause a white band to form on a printed image; determining whether the rotation angle of each unit chip is within the acceptable limit or not; correcting a machine error of each unit chip if it is determined that the rotation angle of each unit chip is not within the acceptable limit; if the rotation angle of each unit chip is within the acceptable limit, adding a plurality of nozzles on an end of each unit chip, determining which of the added nozzles to use based on a predetermined trial printing pattern, and correcting a print error in a horizontal direction that is caused due to a misalignment in the horizontal direction; and correcting a print error in a vertical direction that is caused due to a misalignment between the unit chips in the vertical direction by determining a reference time for voltage pulse application to a heater disposed on a nozzle of the array head of the inkjet printer based on the predetermined trial printing pattern, by variably determining voltage pulse application time thereby adjusting a time interval for an ink ejection from the respective unit chips.